As is known, hollow glass articles are formed in aligned, adjacent molds, and, once molded, are extracted from the respective molds and placed on a supporting surface, from which they are subsequently transferred onto a linear conveyor which feeds them successively to an output of the system.
The glass articles are transferred from the supporting surface to the linear conveyor by means of transfer units, each of which comprises a pickup member for engaging one or more articles to be transferred; a movable supporting arm fitted integrally with the pickup member; a pneumatic linear actuator for moving the supporting arm and the pickup member horizontally to and from the glass articles; and an angular actuator, normally electric, for rotating the supporting arm, about a fixed vertical hinge axis, between a pickup position, to pick the articles off the supporting surface, and a release position, to release the articles onto the linear conveyor.
With the increase in the output rate of molding systems, known transfer units of the type described above have proved increasingly unsatisfactory and unreliable. This is mainly due in part to the presence of pneumatic actuators, the efficiency and controllability of which are severely affected by the thermal conditions in which the transfer unit operates, and in part to the pickup member being connected integrally to the supporting arm, so that it is extremely difficult to set and rapidly correct the pickup positions, the release positions onto the conveyor, and, above all, the travel trajectories of the articles between the pickup and release positions. This has to be done mainly on account of the different shape and size of the articles for manufacture, and the fact that the articles picked up by the pickup member travel along different trajectories to the conveyor, which are not always the best for ensuring correct transfer of the articles, with the result that numerous damaged articles are rejected at the molding system output.